This relates generally to image sensors and, more specifically, to image sensors having image pixels with processed signal storage capabilities.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. Conventional image sensors are fabricated on a semiconductor substrate using complementary metal-oxide-semiconductor (CMOS) technology or charge-coupled device (CCD) technology. The image sensors may include an array of image sensor pixels each of which includes a photodiode and other operational circuitry such as transistors formed in the substrate. The image sensor pixels generate image signals in response to image light. Readout circuitry reads out the image signals from the image sensor pixels.
The image sensors often include processing circuitry coupled to the readout circuitry. The processing circuitry is located around the periphery of the array of image sensor pixels. The processing circuitry performs image processing operations on the read out image signals. The processing circuitry includes memory for storing the processed image signals. The processed image signals are conveyed to frame memory external to the image sensor for storage. The processed image signals stored on the frame memory are further processed by the processing circuitry on the image sensor or by other processing circuitry.
Storing the processed image data on external frame memory can result in undesirably slow processing time, can consume excessive power, and can increase the manufacturing cost and complexity of the imaging system.
It would therefore be desirable to be able to provide image sensors with improved image signal processing and storage capabilities.